How to Test a Faraday Bag in 5 Minutes — The Protocol Used by Pros

Q: What attenuation in dB do I actually need?

Use case determines the floor. (1) Daily privacy and AirTag-shielding: 40–60 dB across 800 MHz – 6 GHz is enough to block consumer wireless. (2) Executive travel against hotel-WiFi MITM and BLE proximity attacks: 60–70 dB minimum. (3) EP-grade principal-carry against state-actor-class adversaries: 70 dB minimum across 30 MHz – 6 GHz, 80+ dB preferred. (4) EMP per MIL-STD-188-125: 80 dB across 14 kHz – 1 GHz. The REVIS-1 Executive Guard tests at 76–85 dB across 30 MHz – 10 GHz — sufficient for use cases (1) through (3) with margin.

Deployment Scenarios

The five-test protocol, step by step.

A friend of yours buys a $30 "Faraday pouch" on Amazon. Drops the phone in. You call the phone. It rings. He looks confused. The pouch's product page shows 90% five-star reviews. Welcome to the consumer Faraday market — a category where the marketing claim and the actual attenuation have nothing to do with each other. Five minutes with your own phone settles every question the spec sheet doesn't.

Cellular call test

Seal the phone in the bag. Ring it from a second phone. Pass = silent. If it rings, audible vibrates, or gets the call, the bag fails the most basic test.

WiFi connection test

Disable cellular. Confirm WiFi connection. Seal in bag. Wait 30 seconds. Refresh browser or check status. Pass = no connection.

Bluetooth ping test

Pair with a known device (laptop, AirPods). Seal in bag. Try to send a file or play media. Pass = connection drops, transfer fails.

GPS lock test

Open Maps, confirm GPS lock. Seal in bag for 60 seconds. Reopen Maps. Pass = lock lost, location stale or unavailable.

FM-radio test (deeper attenuation)

On a phone with FM tuner OR a portable radio, tune to a strong local station. Seal in bag. Pass = signal disappears. Catches bags that block weak cellular but leak high-power broadcast.

REVIS-1 Executive Guard — premium leather construction with verified Faraday shielding

Critical Distinction

How much dB do you actually need?

Use case determines the floor. Don't over-spec for daily privacy; don't under-spec for executive travel.

Use case	Frequency band	dB minimum	REVIS-1 Executive Guard
Daily privacy / AirTag-shielding	800 MHz – 6 GHz	40–60 dB	76–85 dB ✓
Executive travel / hotel-WiFi MITM	800 MHz – 6 GHz	60–70 dB	76–85 dB ✓
EP-grade principal-carry	30 MHz – 6 GHz	70–80 dB	76–85 dB ✓
EMP per MIL-STD-188-125	14 kHz – 1 GHz	80 dB	76–85 dB at 30 MHz – 10 GHz
Anti-jam / state-actor TSCM	9 kHz – 18 GHz	100+ dB	Specialized lab enclosure required

FAQ

Common questions on Faraday bag testing.

Can I really test a Faraday bag at home?

Five tests, five minutes, no equipment beyond your phone. Cellular call, WiFi, Bluetooth, GPS, FM radio. A bag that passes all five blocks the consumer-relevant frequency ranges (800 MHz – 6 GHz wireless plus 88–108 MHz FM). For the EMP-relevant or lab-verified attenuation in dB across the full 30 MHz – 10 GHz band, you need IEEE 299 equipment — but the five-test protocol catches the obvious failures.

Why test FM radio if I only care about phone signals?

FM broadcast is high power — typically 10,000 to 100,000 watts effective radiated power, compared to a cellular signal at fractions of a watt. A bag that blocks weak cellular signals near the noise floor may still leak high-power FM through the same shielding. FM is the deeper test — if the bag silences a strong local FM station, it has meaningful attenuation, not just borderline cellular blocking.

What's the IEEE 299 standard and why does it matter?

IEEE 299 (Standard Method for Measuring the Effectiveness of Electromagnetic Shielding Enclosures) is the lab methodology professional shielding manufacturers use to publish attenuation specs in dB across defined frequency bands. The test requires an anechoic chamber, calibrated transmit/receive antennas, and a network analyzer — not consumer equipment. When a manufacturer claims "76–85 dB across 30 MHz – 10 GHz," that claim should be backed by IEEE 299 (or an equivalent like MIL-STD-188-125) test results from an independent lab. No spec sheet, no claim worth taking seriously.

What attenuation in dB do I actually need?

Use case determines the floor. Daily privacy and AirTag-shielding: 40–60 dB across 800 MHz – 6 GHz is enough to block consumer wireless. Executive travel against hotel-WiFi MITM and BLE proximity attacks: 60–70 dB minimum. EP-grade principal-carry against state-actor-class adversaries: 70 dB minimum across 30 MHz – 6 GHz, 80+ dB preferred. EMP per MIL-STD-188-125: 80 dB across 14 kHz – 1 GHz. The REVIS-1 Executive Guard tests at 76–85 dB across 30 MHz – 10 GHz — sufficient for the first three with margin. See our EMP-spec deep-dive for more.

What does a Faraday bag failing one test but passing others mean?

It means the bag has frequency-dependent shielding gaps. Common failure pattern: passes cellular (narrow band), fails Bluetooth or WiFi (different bands, sometimes higher frequency where small seam gaps become resonant). Cause is usually closure quality — Velcro flaps, inadequate seam overlap, or compromised metallization at high-flex points. A real Faraday bag passes all five home tests because the shielding is broadband; if it passes only some, the bag has localized weak points.

Which bag passes all five tests and meets the procurement spec?

The REVIS-1 Executive Guard. Three independent shielded chambers (laptop, tablet+phone, wallet+keys+RFID), 76–85 dB across 30 MHz – 10 GHz, IEEE 299 test methodology, MIL-STD-188-125 reference frame. Passes all five at-home tests and ships with spec-sheet documentation suitable for procurement auditing. $280 with free U.S. shipping.

Five tests. Five minutes. No spec sheet required.

The same five tests EP details run on field inventory.

EP details. Forensic-handling staff. Privacy-conscious executives. Anyone who reads the spec sheet before the marketing.